1. Field of the Invention
The present invention relates to an information processing apparatus, method of controlling information processing apparatus, and computer program product.
2. Description of the Related Art
Conventionally, a universal serial bus (USB) connection, which connects a host machine with a plurality of peripherals (devices) by serial communication, has been widely used as a method of connecting electronic devices to each other. The USB is an interface standard that provides a hot plugging function, and can be removed or connected during operation of a device.
With the use of the USB, USB host interfaces have been increasingly mounted in image forming apparatuses having a single function such as a laser printer, or image forming apparatuses called multi function printers (MFPs) that implement a plurality of functions including such as scanner function, copying function, print function, and facsimile function in one housing. Various external devices are connected to these image forming apparatuses as external devices through the USB, including optional devices connected at all times to be used such as integrated circuit (IC) card readers and devices temporarily connected to be used such as flash memories.
Meanwhile, in recent years, demands for image forming apparatus having low power consumption have increased. Generally, in an image forming apparatus, low power mode for suppressing power consumption is implemented in such a manner that supply of power to various devices in the image forming apparatus are stopped during a standby state in which an image forming operation such as a print operation is not performed.
In the low power mode, it is desirable to suppress power consumption by stopping supply of power even to a USB host controller mounted in the image forming apparatus when an operation needs not be performed. Japanese Patent Application Laid-open No. 2000-010907 discloses a technique which determines whether or not a USB host controller is to stop depending on whether or not a USB device remains connected to the USB host controller. According to Japanese Patent Application Laid-open No. 2000-010907, power saving can be implemented because the USB host controller can be stopped when the USB device does not remain connected.
Meanwhile, there are various kinds of USB devices that can be connected to the USB host controller. For example, as the USB devices to connect to the USB host controller of the image forming apparatus, there are IC card readers for performing personal authentication, flash memories for storing image data or the like, and the like.
When many kinds of USB devices are connectable as described above, it is considered that whether or not an operation needs to be performed during the low power mode may depend on a kind of a connected USB device. For example, the IC card reader needs to be operating during the low power mode. However, the flash memory needs not be operating during the low power mode.
However, in the past, there was a problem in that it was difficult to determine, for each USB device, whether or not the operation thereof is necessary during the low power mode. For example, in Japanese Patent Application Laid-open No. 2000-010907, when even any one of the USB devices remains connected to the USB host controller, a function of the USB host controller is caused to be effective. However, according to this related art, a determination was not made about whether the function of the USB host controller is caused to be effective or ineffective for each USB device.
There is a need to more efficiently perform power saving of an apparatus in which a USB host controller is mounted.